This invention relates in general to the isolation of specific ribonucleic acid molecules and, more specifically, to the detection and isolation of endorphin mRNA.
Recently, considerable research effort has been expended in investigating the intricate relationship between genes and proteins. A wide variety of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules have been detected and have been found to perform a variety of biochemical functions. Some ribonucleic acid polymers have been found to serve a "messenger" function, providing a template guiding definite sequences of amino acids in the assembly of proteins. These messenger RNA (or mRNA) molecules, if detected and isolated, can be used to "manufacture" DNA molecules having the capability of producing selected useful amino acid sequences, such as insulin.
Endorphin is polypeptide hormone produced by cells in the pituitary gland, brain, gut and in the alpha cells of the Islets of Langerhans. It has been called "natural morphine." Small amounts have been isolated, appearing to be part of a much larger straight chain polypeptide. Endorphin has been found to be useful in producing a slowed movement of the gut, relaxing smooth muscle and preventing pain.
Enkephalin may have the sequence: Tyrosine-Glycine-Glycine-Phenylalanine-Leucine ("Leu-enkephalin") or Tyrosine-Glycine-Glycine-Phenylalanine-Methionine ("Met-enkephalin"). Mixtures of these forms, which have quite similar properties, are generally simply referred to as enkephalin.
While the enkephalin five amino acid sequence may exist alone, it is most effective when incorporated into the longer (31 amino acid) endorphin sequence. However, no satisfactory method exists in the prior art for the detection or isolation or reasonable quantities of the several types of endorphin mRNA. Thus, there is a continuing need for an improved method for isolating and purifying endorphin mRNA.